V10 exhaust note(technical help)

[deadpres]

Alright guys this has been bothering me since last night and I've been trying to research it as much as possible. The V10 Viper has a unique sound which we're all aware of..I don't quite understand it yet so I thought maybe a few technical members could chime in to help me out

Dodge uses a typical cross-plane crankshaft in their V8 but by adding two cylinders would throw off the 'even-firing'. My understanding is..a 90deg V10 block requires crank pins to be spaced 72deg apart to keep that same 'even-firing'..which helps with balancing/vibration. And from what I've collected online, the Viper crankshaft is NOT designed on the 72deg crank pin design. An 'uneven-firing' order was established using a 90deg and 54deg interval which creates that unique sound. SO, this is where I'm lost. If each journal has shared pins(2 rods per journal) then how is it mathematically possible to reach exactly 720deg crankshaft rotation with every cylinder firing once? :shrug::??::shrug:See math below

Side notes:
4-stroke engines require 720deg to complete every 'stroke'
Viper crankshaft is NOT split-pin design(99% sure)

Example: (1 example of several that could be used)
3 journals(6 rods) 90deg from each other
90 x 6 = 540deg
2 journals(4 rods) 54deg from each other
54 x 4 = 216deg
540 + 216 DOES NOT equal 720deg

NOW, say one bank of 5cylinders is only 90deg and the other bank of 5 is only 54deg..

5pins 90deg from each other
90 x 5 = 450
5pins 54deg from each other
54 x 5 = 270
450 + 270 EQUALS 720deg

So, I have it figured out..right? Wrong. How can a shared pin journal have a 90deg and 54deg pin location? And like I posted before, plus I looked at pictures online, the crankshaft is not split-pin design.

Am I over thinking this? Somebody please help before I rip my hair out :bash: Also, If any technical info. I posted is incorrect, please let me know!

 

[rotor_powerd]

A quick Google gives:

"Each piston fires once every 2 rotations, or 720 degrees.

In this scenario: 1, 10-9, 4-3, 6-5, 8-7, 2

comma = 90 degrees
dash = 54 degrees

Fire 1, rotate 90
Fire 10, rotate 54
Fire 9, rotate 90
Fire 4, rotate 54
Fire 3, rotate 90
Fire 6, rotate 54
Fire 5, rotate 90
Fire 8, rotate 54
Fire 7, rotate 90
Fire 2, rotate 54
----------------------
Tot. Degrees: 720"

 

[deadpres]

^^^ Thanks for the useless information..I already posted the 90 and 54deg interval. Obviously you didnt read my entire post

 

[GodStang]

There is a great thread on here on this exact discussion. I will see if I can find it.

Never mind you already saw this:
http://www.svtperformance.com/forum...ne-firing-order-how-impacts-engine-sound.html

 

[SweetSVT99]

^^^ Thanks for the useless information..I already posted the 90 and 54deg interval. Obviously you didnt read my entire post

Easy killer...

 

[deadpres]

There is a great thread on here on this exact discussion. I will see if I can find it.

Never mind you already saw this:
http://www.svtperformance.com/forum...ne-firing-order-how-impacts-engine-sound.html

Hha I remember that thread. 2 years ago..Wow, time flies! Maybe James Snover will chime in?

Easy killer...

I forgot about the typical svtp response..'here, let me google that for you'

 

[Ironhand]

The 6.8L does not have a common rod journal. It is what is called a split pin crank where each rod bolts to its own section of the crank.

Splitting the pins doesnt help with balancing but prevents two opposed cylinders from firing at the same time.

This is what a split pin crank looks like. This is how you get a V10 in a 90 degree block to fire at 72 degrees.

 

[thepizz]

Obviously you didnt read my entire post

because TL;dr

 

[James Snover]

It's my understanding the Viper does not have a split-pin crank, and is what is referred to as an odd-firing engine. This gives it a characteristic uneven exhaust note. When I first heard of the Viper V-10, I assumed it had to be a 72-degree block. Nope, it's a 90.

Odd-firing sucks. I can't argue with the results, but I hate odd-firing engines. Chrysler could have made a 60-degree block V-12 with a 120-degree crank, ala the Rolls Royce/Packard Merlin V-12's of WWII fame, and then they would have something to really talk about. But no, once again Chrysler retreats from engineering greatness.

 

[deadpres]

The 6.8L does not have a common rod journal. It is what is called a split pin crank where each rod bolts to its own section of the crank.

Splitting the pins doesnt help with balancing but prevents two opposed cylinders from firing at the same time.

This is what a split pin crank looks like. This is how you get a V10 in a 90 degree block to fire at 72 degrees.

Ford V10..I understand this engine which also includes balance shafts. However, the Viper V10 is not a split-pin in a 90deg block.

because TL;dr

Let me guess..you know the title of this thread but have no idea what we're discussing?

It's my understanding the Viper does not have a split-pin crank, and is what is referred to as an odd-firing engine. This gives it a characteristic uneven exhaust note. When I first heard of the Viper V-10, I assumed it had to be a 72-degree block. Nope, it's a 90.

Odd-firing sucks. I can't argue with the results, but I hate odd-firing engines. Chrysler could have made a 60-degree block V-12 with a 120-degree crank, ala the Rolls Royce/Packard Merlin V-12's of WWII fame, and then they would have something to really talk about. But no, once again Chrysler retreats from engineering greatness.

Thanks for the input. I think what I really need to do is look at a drawing(blueprint) of the Chrysler V10 crankshaft and maybe I'll understand it better. Wouldn't hurt to look at one in person either..I bet a particular shop out in Sealy has plenty laying around lol

 

[Blade Runner]

Why is it then, that the Drag Pak V10 Challenger sounds so damned beastly? To me, it sounds nothing like the Viper. :shrug:

 

[mifordman]

viper crank has 5 shared con rod journals at 72* apart and a 90* block design

5 x 72 = 360

360 x 2 = 720

 

[IUP99snake]

Correct me if I'm wrong, but I'm pretty sure that they changed the firing order, or the crankshaft characteristics in the newer 8.4L V10 compared to the older 8.0L V10.

Notice how the 8.0L V10 sounds raspy and higher pitched, whereas their newer 8.4L counterpart sounds much deeper. I don't think that deeper pitch has much to do with just a 400cc bump in displacement. It's something to do with the firing order, whether it be a split pin or common pin crank, or perhaps swapping the firing stroke on certain cylinders much like the non-HO vs. HO firing order on the pushrod 5.0 motors that has to do with the cam characteristics.

Most of what I said is just a guessing compilation from information I've read about, seen on TV, or overheard in conversations. I don't know if it's true or not, but that's just my guess.


I really want to do a V10 swap mustang. I know there aren't many performance parts for the 6.8L V10, but there are still things you can do to it like any modular motor to increase the performance.

*Start with a 3V motor
*CNC port the cylinder heads
*Add Oversized Valves
*Add a set of 10 Manley H-Beam Connecting Rods from a 5.4 based motor
*Set of 10 Forged pistons and bump the compression as high as possible given the fuel that's going to be run. I'd say 11:1 on 93 or 13:1 on E-85 or LNG or LP.

These are just the basic mods, not including crank and oiling system modifications.

I don't think there are any sort of aftermarket V10 cams, but I'm sure Crane or Comp may custom grind a set of cams based on a popular V8 profile given this combination.